/* This file is part of the Palabos library.
 *
 * The Palabos softare is developed since 2011 by FlowKit-Numeca Group Sarl
 * (Switzerland) and the University of Geneva (Switzerland), which jointly
 * own the IP rights for most of the code base. Since October 2019, the
 * Palabos project is maintained by the University of Geneva and accepts
 * source code contributions from the community.
 *
 * Contact:
 * Jonas Latt
 * Computer Science Department
 * University of Geneva
 * 7 Route de Drize
 * 1227 Carouge, Switzerland
 * jonas.latt@unige.ch
 *
 * The most recent release of Palabos can be downloaded at
 * <https://palabos.unige.ch/>
 *
 * The library Palabos is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * The library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/** \file
 * Utilities for 3D multi data distributions -- header file.
 */

#include "multiBlock/redistribution3D.h"

#include <cstdlib>

#include "core/globalDefs.h"

namespace plb {

RandomRedistribute3D::RandomRedistribute3D(pluint rseed_) : rseed(rseed_) { }

MultiBlockManagement3D RandomRedistribute3D::redistribute(
    MultiBlockManagement3D const &original) const
{
    ThreadAttribution const &originalAttribution = original.getThreadAttribution();
    SparseBlockStructure3D const &originalSparseBlock = original.getSparseBlockStructure();

    std::map<plint, Box3D> const &domains = originalSparseBlock.getBulks();
    std::vector<std::pair<plint, plint> > blockToProc(domains.size());
    std::map<plint, Box3D>::const_iterator it = domains.begin();
    for (plint pos = 0; it != domains.end(); ++it, ++pos) {
        plint blockId = it->first;
        plint procId = originalAttribution.getMpiProcess(blockId);
        blockToProc[pos] = std::pair<plint, plint>(blockId, procId);
    }

    srand(rseed);
    plint numExchange = (plint)blockToProc.size() * 10;
    for (plint iExch = 0; iExch < numExchange; ++iExch) {
        plint id1 = rand() % blockToProc.size();
        plint id2 = rand() % blockToProc.size();
        std::swap(blockToProc[id1].second, blockToProc[id2].second);
    }

    ExplicitThreadAttribution *newAttribution = new ExplicitThreadAttribution;
    for (pluint i = 0; i < blockToProc.size(); ++i) {
        newAttribution->addBlock(blockToProc[i].first, blockToProc[i].second);
    }

    return MultiBlockManagement3D(
        originalSparseBlock, newAttribution, original.getEnvelopeWidth(),
        original.getRefinementLevel());
}

}  // namespace plb
